Purification of rubber distillates



Patented Apr. 28, 1936 UNHTED STATES PATENT OFFIQE PURIFICATION OFRUBBER DISTILLA'IES of Delaware No Drawing. Application October 11,1935, Serial No. 44,557. In Great Britain November 6, 1934 4 Claims.

This invention relates to the art of preparing solvents of organicorigin and has for its object to provide an improved method forpreparing and deodorizing solvents of this nature.

It is known that the destructive distillation of rubber preferably wasterubber, produces a liquid of low viscosity that has valuable solventproperties.

Certain fractions of the said distillate which are substantiallyisoprene-free may for instance be used in the reclamation ordevulcanization of waste rubber whilst crude rubber may be dissolved inthe same or other fractions, as set forth in my co-pending applicationSer. No. 721,760 filed April 21, 1934, wherein it is described that thedestructive distillation of the rubber produces a cracking effect on theheavier oils with the result that the distillate contains besidesisoprene, an increased proportion of more volatile or light oils.

One disadvantage in the use of the distillate of rubber as a solvent hasbeen the characteristic unpleasant odor of the liquid, whilst its coloris unattractive.

By cracking, deodorizing and decolorizing the distillate I produce ageneral purpose solvent of considerable use in industry.

It will be found that most ordinary organic substances are soluble insuch a solvent and that it will mix readily with most organic liquids.

The lighter fractions, being more spiritous than oily in nature may beused for such purposes as dry cleaning and de-greasing.

For toilet purposes the solvent, unlike petrol benzine and similarsolvents will remove grease and oil from the skin without leaving it dryand scaly.

Wax readily dissolves in the solvent and wax polishes may thus beprepared with the solvent as a substitute for the more usual turpentine,or the solvent may be used in admixture with turpentine for any of themore usual purposes to which turpentine is put.

By rectification, the flash point of the solvent may be adjusted to anyreasonable degree.

In carrying the invention into effect, rubber preferably wastevulcanized rubber is subjected to dry destructive distillation in aclosed retort. The distillate is a heavy dark colored oil having astrong penetrating smell.

After this oil has been freed from water it is dealt with in thefollowing manner.

By fractional distillation of the rubber distillate, the fraction whichdistils over up to about 200 C. is collected, whilst the residue is usedin connection with reclaiming rubber.

The light fraction referred to distilling up to about 200 C. is found topossess a somewhat unpleasant odor, whilst its color is dark andunattractive for a general purpose solvent.

In order to remove the odor and to improve the color the solvent isheated with a metallic chloride such as mercuric chloride, zinc chlorideor ferric chloride, preferably in the form of a dry salt. The proportionof salt may be varied according to the degree of decolorization anddeodorization desired. Generally 2% to 7% by weight may be used.

On re-distilling, the solvent is found to be deodorized and practicallydecolorized, the color being a light amber or straw color.

The treatment with chlorides may be carried out before the lightfraction is separated from the distillate, and in this case the odor ofthe heavy residue is also improved. The use of zinc chloride ispreferred on account of the fact that zinc oxide which is readilyobtained as a by-prodnot in the destructive distillation process ofwaste vulcanized rubber e. g. waste tire stocks, can be easily separatedand converted into the chloride.

With the detailed description given above, it will be obvious thatmodifications will suggest themselves Without departing from theprinciple of the invention, and it is not desired to limit the inventionotherwise than as set forth in the appended claims.

Having thus described my invention, what I claim and desire to protectby Letters Patent is:

1. A process of preparing an organic solvent from rubber which comprisesdeodorizing and decolorizing a rubber distillate by heating the same inthe presence of a metallic chloride selected from the group consistingof mercuric chloride, ferric chloride and zinc chloride, said rubberdistillate corresponding to the fraction distilling over up to about 200C.

2. A process of preparing an organic solvent from rubber which comprisessubjecting the rubber to destructive distillation, fractionallydistilling the rubber distillate, recovering the fraction distillingover up to about 200 0., heating said distillate fraction with ametallic chloride selected from the group consisting of mercuricchloride, ferric chloride and zinc chloride, said rubber distillatecorresponding to the fraction distilling over up to about 200 C. todeodorize and decolorize the distillate, and separating the deodorizedand decolorized distillate from metallic chloride.

3. A process of preparing an organic solvent from rubber which comprisesdeodorizing and decolorizing a rubber distillate by heating the same inthe presence of zinc chloride selected from the group consisting ofmercuric chloride, ferric chloride and zinc chloride, said rubberdistillate corresponding to the fraction distilling over up to about 200C.

4. An organic solvent derived from a process as set forth in claim 1 andcharacterized in having a light amber or straw color.

FRANCIS NORMAN PICKETT.

